Where is the "Local Coordinates" option for Inflow Object?
Since you can use Source and Normal settings, Local Coordinates are a bit useless.
Inflow usually emits fluid only from one direction, there is no specific reason to use whole surface of object as inflow.
It means you can use a disk with same efficiency.

Originally taken from https://blenderartists.org/t/lets-talk-about-mantaflow/644346/908?u=vklidu